Re: T400 suspend/resume regression -- bisected to a mystery merge commit

[Linus Torvalds <torvalds@linux-foundation.org>]

On Thu, 1 Oct 2009, Theodore Tso wrote:
> 
> commit 8c3ee48dabee782d470cc4c7048ea64bb8b7d1cb
> Author: Theodore Ts'o <tytso@mit.edu>
> Date:   Thu Oct 1 20:39:03 2009 -0400
> 
>     Revert "timekeeping: Update clocksource with stop_machine"
>     
>     This reverts commit 75c5158f70c065b9704b924503d96e8297838f79.

Hmm. Looks good. But you didn't cc most of the people actually involved 
with that commit (Martin who is the author, and John who acked it).

I think the revert is the right thing to do, especially as that 
'clocksource_mutex' looks totally bogus. Either the thing is protected by 
'stop_machine' or it's not. In neither case does it seem to make any sense 
to replace a spinlock with a mutex. 

And resuming anything with a big mutex is crazy anyway. 

That said, I do wonder if this is already fixed. See commit 
89133f93508137231251543d1732da638e6022e1:

    clocksource: Resume clocksource without taking the clocksource mutex

which already undid the part that probably mattered for you. That said, I 
still do think that that mutex is dubious, so maybe we should undo it all.

		Linus